Detergent active materials

ABSTRACT

The inorganic salt content of alkane sulphonates, alcohol sulphates and olefin sulphonates can be reduced by treating the detergent active with a mixture of water and isopropanol and/or isobutanol with the conversion of bisulphite ions into sulphite ions. The treatment is performed under reflux at a temperature between boiling and 20*C below boiling. A proportion of the inorganic material precipitates and is separated from the liquor which contains the active.

United States Patent Malhotra [54] DETERGENT ACTIVE MATERIALS [72]Inventor: Virender Nath Malhotra, Bebington,

England [73] Assignee: Lever Brothers Company, New

York, NY.

[22] Filed: July 24, 1970 [21] Appl. N0.: 58,023

[ 1 Foreign Application Priority Data July 25, 1969 Great Britain..37453/69 [52] US. Cl "260/513 R, 252/535, 252/554 [51] Int. Cl. ..Clldl/l2 [58] Field of Search ..252/161, 535, 554; 260/513,

[56] References Cited I UNITED STATES PATENTS 3,541,140 11/1970 Murphyet a1. ..260/513 3,186,948 6/1965 Sweeney ..252/161 3,496,226 2/1970Schvierer ..260/513 2952639 9/1960 Sullivan et a1. ..252/161 2,316,7194/1943 Russell ..260/400 2,810,745 10/1957 Wolski ..260/504 3,031,4984/1962 Pengilly .260/ 5 05 FOREIGN PATENTS OR APPLICATIONS 6,600,2827/1967 Netherlands 1,093,103 11/1967 Great Britain OTHER PUBLICATIONSHackh s Chemical Dictionary, 3rd Ed., Copyright 1944, McGraw-I-Iill BookCo., Inc., p. 151.

Primary Examiner-Leon D. Rosdol Assistant ExaminerP. E. WillisAttorney-Louis F. Kline, Jr., Melvin H. Kurtz and Edgar E. Ruff ABSTRACIThe inorganic salt content of alkane sulphonates, alcohol sulphates andolefin sulphonates can be reduced by treating the detergent active witha mixture of water and. isopropanol and/or isobutanol with theconversion of bisulphite ions into sulphite ions. The treatment isperformed under reflux at a temperature between boiling and 20C belowboiling. A proportion of the inorganic material precipitates and isseparated from the liquor which contains the active.

8 Claims, 6 Drawing Figures PATENTED B I9 3.696.143

sum 2 or 6 1 [BU/LU 70/30 80/20 PATENTEDnms m2 3 696. 143

sum 3 or e DETERGENT ACTIVE MATERIALS Theinvention is particularlyuseful for reducing the inorganic salt content of such a product.

Many methods for separating inorganic salts have been tried but all forone or more reasons have been unsatisfactory.

The invention provides a method of reducing the inorganic materialcontent of a detergent active material comprising the steps of;

i. forming the active powder or paste into a monophase solution with asolvent mixture of water and isopropyl alcohol, and/ortertiary butylalcohol.

ii. converting any bisulphite ions present into sulphite ions before orafter (if necessary),

iii. heating under reflux in a temperature range from boiling to 20cbelow to precipitate a proportion of the inorganic material,

iv. separating the precipitated material from the liquor and t v.recovering the active material from the liquor.

The bisulphite conversion can be performed before the monophase solutionis formed. It has been found advisable to seed the solution to speed upthe process of precipitation and thus increase the amount of inorganicmaterial separated.

The term monophase refers to the liquid phase which must exist as asingle phase although it may contain some undissolved solid materialwhen first formed.

The ratio of water to alcohol in the solvent mixture will be determinedby the user of the invention having regard to the amount of inorganicmaterial in the detergent active material. Thus a good separation ofinorganic material is achieved in the region of the azeotropphite withan alpha-olefins. Alpha-olefins normally contain antioxidants tominimize their deterioration in the presence of atmospheric oxygen. Ithas been found that pretreatment of alpha-olefins as described in GBPat. No. 1,159,728 removes a substantial proportion of suchantioxidants.

The reaction of alpha-olefin with sodium bisulphite gives a productcontaining sodium sulphate together with sodium sulphite and sodiumbisulphite. It has been found that better removal of salt from alkanesulphonate is obtained if sodium bisulphite present is converted tosodium sulphite by addition of alkali prior ic ratio but because of thegreatly reduced solubility of the detergent active material a relativelylarge amount of solvent mixture is required. As the temperature at whichthe solvent mix is heated is reduced the separation improves, because ofthe reduced solubility of the active material. The applicant has foundthat a useful separation of inorganic material is achieved attemperatures down to 20C below the boiling point of the mixture.

To use sodium alkane sulphonate as an active in some specialformulations, it is desirable to have the concentration of inorganicmaterial below 2 percent. This is achieved by using a solvent mixcontaining more than percent by weight of isopropyl alcohol or more than78 percent by weight of tertiary butanol at boiling reflux. The upperconcentration limit will be determined by the amount of alcohol the useris prepared to use per unit of detergent active.

Sodium alkane sulphonate suitable for use as a detergent active usuallycontains from eight to 22 carbon atoms in a straight chain with thesulphonate group at one end of the chain. Such compounds can be preparedby, for instance, free-radical reaction of sodium bisulto the alkanesulphonate being heated in solution by aqueous alcohol. This obviates atendency for a liquid phase containing much of the inorganic salts toform; to separate the inorganic salts once this liquid phase forms isespecially difficult.

The invention is particularly applicable to sodium alkane sulphonateprepared by the free-radical reaction of sodium bisulphite withalpha-olefin in aqueous isopropanol. The weight ratio of isopropanol towater is usually less than 65:35 during the addition reaction, and aftercompletion the concentration of isopropanol can be brought to thedesired level for salt separation.

Experiments to illustrate the invention will now be described withreference to FIGS. 1 and 2 which show the reduction in inorganic contentof sodium alkane sulphonate using respectively isopropanol and tertiarybutanol in the concentrations with water shown.

In FIGS. 1 and 2, axis A shows the concentration of inorganic materialin the detergent active and axis B shows the ratio by weight of theisopropanol/water and tertiary butanol/water mixtures.

In each of these figures there are three graphs which were determinedunder the following conditions I. Without conversion of bisulphite Y ll.With conversion of bisulphite III. With seeding of the heated mix.

In order to determine graph 1 250 g, 225 g, 150 g, 150 g, and 95 g ofcrude sodium c alkane sulphonate containing respectively 12.25 percent,7.75 percent, 6.83 percent, 8.5 percent and 7.75 percent of inorganicmaterial were boiled under reflux in 65 percent (500 g), percent (580g), 72 percentv (500 g), 75 percent (500 g) and percent (500 g) byweight of isopropanol in water. After precipitation of the inorganicmaterial the liquor was filtered and the inorganic material contentmeasured.

This procedure was repeated, to provide Graph ll, after the sodiumbisulphite had been converted in the sulphite by addition of thecalculated amount of 25 percent sodium hydroxide solution. Pureisopropanol was added to retain the isopropanol/water ratio at thedesired level andthe mixture boiled for three hours.

The procedure for Graph ll was repeated with the further additional stepof seeding. The mixture in each sample was seeded with 0.2 g of sodiumsulphate and 0.2 g of sodium sulphite. After seeding the mixture wasstirred for 3 hours before separating the precipitate and determiningthe inorganic material content of the filtrate.

Repeating the experiments at room temperature (20C) using 500 g of 70percent by weight of isopropanol in water with 33 g of crude active, itwas found that a good separation of inorganic material was achieved.However, a larger quantity of solvent is required which not only leadsto greater expense in the purchase of isopropanol but also to therequirement for a larger crystallizer and increased amounts of steam forrecovery of the isopropanol.

FIG. 2 shows the results of experiments using tertiary butanol andstarting with a crude c sodium alkane sulphonate containing 12.25percent inorganic material i.e. sodium bisulphite, sulphite andsulphate.

With both these solvents it has been found that an effective separationof inorganic material is achieved at temperatures down to C below theboiling point.

The process of the invention allows the inorganic salt content to bereduced to the region of 2 percent. The use of an isopropanol/watermixture containing at least 70 percent by weight of the alcohol or atertiary butanol/water mixture containing at least 78 percent by weightof the alcohol provides an alkane sulphonate with an inorganic materialconcentration of not more than 2 percent.

The invention also extends to processes for a reduction of inorganicmaterial content in detergent active materials.

A preferred process according to the invention consists of the followingstages;

a. neat isopropanol or an azeotrope of isopropanol and water is added tosodium alkane sulphonate in aqueous isopropanol to bring the weightratio of isopropanol to water to greater than 70:30;

b. crystalline inorganic salt is separated at a temperature from 20Cbelow reflux to reflux;

c. the aqueous isopropanol is removed to give the sodium alkanesulphonate with reduced inorganic salt content;

d. the aqueous isopropanol is fed to a distillation column where it isseparated into water and isopropanol or azeotrope; and,

e. the isopropanol or azeotrope is used in stage (a).

It should be noted that the separation in stage (d) need not becomplete; azeotrope can be formed. Likewise the water can contain someisopropanol; the water will in any case contain a major proportion ofany oily matter originally mixed with the sodium alkane sulphonate, forinstance, paraffin and residual olefine. This is a further advantage forthis process. Also the inorganic salts separated at stage (b) will be ina convenient form to extract sodium sulphite for re-use in thebisulphite reaction with olefin for making the alkane sulphonate.

Preferably in stage (b) crystallization is initiated by the addition ofseed quantities of crystalline sodium sulphite and sulphate.

In a particularly preferred process according to the invention aqueousisopropanol, in which the reaction between a-olefin and sodiumbisulphite has occurred, is flashed off from the sodium alkanesulphonate and inorganic salts. Neat isopropanol or, preferably, anazeotrope of isopropanol and water is added to the sodium alkanesulphonate and inorganic salts and the solution so formed heated at atemperature from 20C below reflux to reflux so that the inorganic saltsstart to crystallize. Crystalline inorganic salts are then separated andisopropanol and water flashed off to give sodium alkane sulphonate withreduced inorganic salt content.

Preferably the aqueous isopropanol, in which the reaction has occurred,and the water and isopropanol after separation of crystalline inorganicsalts are fed to a distillation column to give an azeotrope ofisopropanol and water and water which contains the bulk of any oilymatter originally mixed with the sodium alkane sulphonate.

By the use of flash evaporators before the distillation column foamingin the column is reduced in comparison with a procedure within the scopeof the invention where, after separation of crystalline inorganic salts,the sodium alkane sulphonate and isopropanol and water are separated ina distillation column.

Also use of a flash evaporator to flash off the isopropanol and water,in which the reaction between a-olefin and sodium bisulphite hasoccurred, before the sodium alkane sulphonate is heated with isopropanoland water at a temperature from 20C below reflux to reflux enables anazeotrope of isopropanol and water to be added to the sodium alkanesulphonate for the for the crystallization rather than neat isopropanolor azeotrope and neat isopropanol. Neat isopropanol is expensive toproduce.

Use of the flash evaporator also enables the amount of azeotrope andhence the size of the crystallizers to be minimized. The amount ofazeotrope added at the crystallization stage can be related to thesolubility of the active at the temperature concerned.

Preferably the distillation column should be operated under slightvacuum. Thereby the operation of the flash evaporators is aided.

Examples of processes according to the invention will now be describedwith reference to FIGS. 3 and 4.

In FIG. 3, an isopropanol and water solution of sodium alkane sulphonatetogether with organic and inorganic impurities is produced, A. To thismixture is added sufficient sodium hydroxide, a, to convert any residualsodium bisulphite to sodium sulphite. The mixture is then fed to acrystallizer, B, where it is heated to or maintained at refluxtemperature, ca 82C, and sufficient isopropanol, b, is added to raisethe weight ratio of isopropanol to water in the mixture to :30.Crystallization of inorganic salts occurs and the crystalline salts, c,are separated in centrifuge, C.

The isopropanol and water solution of sodium alkane sulphonate is fed toa flash-evaporator D. Sodium alkane sulphonate, d, with a reducedinorganic salt content is obtained. The flashed off isopropanol andwater, 2, is fed to an azeotropic or extractive distillation column, E,where the isopropanol, f, and water, g, are at least to a major extentseparated.

Referring now to FIG. 4 isopropanol and water solution of sodium alkanesulphonate together with organic and inorganic impurities is produced.To this mixture is added sufficient sodium hydroxide, a, to convert anyresidual sodium bisulphite to sodium sulphite. The mixture is then fedto a tubular flash dryer, b backed by a flash chamber, C Sodium alkanesulphonate and inorganic impurities are fed, c, to Crystallizers I.

lsopropanol and water vapors d, from the flash chamber, C are fed to acyclone separator, D Sodium alkane sulphonate, c, from the separator isfed to the Crystallizers, I. The vapors d, from the separator are fed toa distillation column, E, where they are fractionated into water, e,which contains the bulk of the organic impurities in the sodium alkanesulphonate, and an azeotrope, f, of isopropanol and water.

The distillation column, E, is backed by a condenser, F, and a steamejector system, G.

A proportion of the azeotrope, g, from the condenser, F, is returned tothe distillation column. The remainder is fed to a storage vessel, H.Provision is made for isopropanol, h, to be added to the storage vessel,H, to compensate for isopropanol lost in the system. Sufficient of theazeotrope or azeotrope enhanced with isopropanol is fed, i, to thecrystallizers, I, to dissolve the sodium alkane sulphonate at atemperature from 20C below reflux to reflux. In a metafilter, J,crystalline inorganic salts, j, are separated.

Isopropanol and water k, from the metafilter, J, are

fed to a second tubular flash dryer, B backed by a flash chamber, C andcyclone separator, D Sodium alkane sulphonate with a reduced inorganicsalt content, l, is obtained from the flash chamber, C and the cycloneseparator D The isopropanol and water vapors m, from the cyclone theseparator, D are fed to the distillation column, E.

In a modification of the apparatus shown in FIG. 4 a second distillationcolumn is provided immediately before dryer B Isopropanol and watervapors are fed back to the distillation column E and the concentratedalkane sulphonate solution supplied to dryer B This invention relatesalso to an improvement in the process of reacting a bisulphite materialfor example the sodium salt, with an alpha-olefinic material to give analkane sulphonate detergent active. The reaction is normally performedin a reaction medium comprising a mixture of isopropanol and water. Theinventor has found that the amount of isopropanol required in thereaction mixture per ton of active per hour can be minimized to givereduced requirements for raw materials and equipment.

The invention is directed to a process wherein a bisulphite material isreacted with a C to C alpha olefin in a reaction medium comprisingisopropanol and water characterized in that the weight of alpha olefintaken as starting material is sufficient to give an amount of alkanesulphonate after conversion; the ratio between the amount of alkanesulphonate and total amount of isopropanol, water and alkane sulphonatebeing in the range of 0.2 to 0.3. For a c olefin the ratio is preferablyabout 0.25 and for a C -C olefin the ratio is preferably about 0.3.

FIGS. 5 and 6 show respectively the tons of isopropanol required per tonof active produced per hour (axis D) plotted against the ratio of theweight of active produced to the total weight of active, isopropanol andwater (axis C). It is seen that minima occur in the graphs at 0.25 inFIGS. 5 which relates to C -C alpha olefins and at 0.30 in FIG. 6 whichrelates to C -C alpha olefins.

In an example to demonstrate the invention 2,580 lbs of C alpha olefin(available olefins 85 percent) were added to a reaction vessel with4,460 lbs of isopropanol and 3,940 lbs of water. The mixture was heatedto its boiling point and reacted with a sodium bisulphite solutionconsisting of 1,255 lbs of sodium metabisulphite (97.5 percent pure),and 125.5 lbs of sodium hydroxide (98 percent pure) dissolved in 2.761

lbs of water. The final product was 1.66 tons (3,733 lbs) of sodiumalkane sulphonate. The ratio as defined by the invention was 0.25.

The example was repeated for C olefin (available olefin present 89percent) using 3,300 lb of olefin, 4,125 lb of isopropanol and 3,186 lbof water in the reaction vessel. The solution added consisted of 1,370lb of sodium metabisulphite (97.5 percent pure), 137 lb of sodiumhydroxide (98 percent pure) and 3,014 lb of water. The final product was4,480 lb of sodium alkane sulphonate and the ratio as defined by theinvention was 0.305.

What is claimed is:

1. A process for reducing the inorganic salt content of an alkanesulphonate containing about eight to about 22 carbon atoms, prepared byreacting an alkali metal bisulphite with an olefinic compound,comprising the steps of;

i. preparing a monophase solution of the sulphonate in a solvent mixtureof water and at least percent by weight of a compound selected from thegroup consisting of isopropanol, tertiary butanol, and mixtures thereof,

ii. adding a basic material to the monophase solution to convertbisulphite ions to sulphite ions.

'iii. heating the solution under reflux at a temperature in the rangefrom about the boiling point of the solution to about 20C below thispoint,

iv. separating the precipitated inorganic salts from the solution, and

v. recovering the alkane sulphonate from the solution by evaporation ofthe mixed solvent.

2. A process according to claim 1 wherein the solvent mixture containsat least 78 percent by weight of tertiary butanol.

3. A process according to claim 1 wherein a crystalline materialselected from the group consisting of alkali metal bisulphites andsulphates is added to the solution to assist crystallization of theinorganic salts.

4. A process according to claim 1 wherein the solvent mixture isazeotropic.

5. A process for reducing the inorganic salt content of an alkanesulphonate containing about eight to about 22 carbon atoms prepared byreacting an alkali metal bisulphite with an olefinic compound,comprising the steps of:

i. adding a basic material to the alkane sulphonate reaction product toconvert bisulphite ions to sulphite ions,

ii. preparing a monophase solution of the alkane sulphonate in a solventmixture of water and at least 70 percent by weight of a compoundselected from the group consisting of isopropanol tertiary butanol andmixtures thereof,

iii. heating the solution under reflux at a temperature in the rangefrom about the boiling point of the solution to about 20C below thispoint,

iv. separating the precipitated inorganic salts from the solution, and

v. recovering the alkane sulphonate from the solution by evaporation ofthe mixed solvent.

6. A process according to claim 5 wherein the solvent mixture containsat least 78 percent by weight of tertiary butanol.

7. A process according to claim wherein a crystalline material selectedfrom the group consisting of alkali metal bisulphites and sulphates isadded to the solution to assist crystallization of the inorganic salts.

8. A process according to claim 5 wherein the sol- 5 vent mixture isazeotropic.

2. A process according to claim 1 wherein the solvent mixture containsat least 78 percent by weight of tertiary butanol.
 3. A processaccording to claim 1 wherein a crystalline material selected from thegroup consisting of alkali metal bisulphites and sulphates is added tothe solution to assist crystallization of the inorganic salts.
 4. Aprocess according to claim 1 wherein the solvent mixture is azeotropic.5. A process for reducing the inorganic salt content of an alkanesulphonate containing about eight to about 22 carbon atoms prepared byreacting an alkali metal bisulphite with an olefinic compound,comprising the steps of: i. adding a basic material to the alkanesulphonate reaction product to convert bisulphite ions to sulphite ions,ii. preparing a monophase solution of the alkane sulphonate in a solventmixture of water and at least 70 percent by weight of a compoundselected from the group consisting of isopropanol tertiary butanol andmixtures thereof, iii. heating the solution under reflux at atemperature in the range from about the boiling point of the solution toabout 20*C below this point, iv. separating the precipitated inorganicsalts from the solution, and v. recovering the alkane sulphonate fromthe solution by evaporation of the mixed solvent.
 6. A process accordingto claim 5 wherein the solvent mixture contains at least 78 percent byweight of tertiary butanol.
 7. A process according to claim 5 wherein acrystalline material selected from the group consisting of alkali metalbisulphites and sulphates is added to the solution to assistcrystallization of the inorganic salts.
 8. A process according to claim5 wherein the solvent mixture is azeotropic.